Blonde Door

A blonde keeps having the same weird dream, so she goes to her psychologist.
psychologist: "What is your dream about?"
Blonde: "I am being chased by a vampire..."
psychologist: "So, where are you in this dream?"
Blonde: "I am running in a hallway."
psychologist: "Then what happens?"
Blonde: "Well, that's the weird thing. In every single dream, the same thing happens. I always come to a door, but I can't open it. I keep pushing the door and pushing the door, but it won't budge!"
psychologist: "Does the door have any letters on it?"
Blonde: "Yes."
psychologist: "And what do these letter spell?"
Blonde: "P.. U... L... L..."